Carburetor needle valves



Jan. 19, 1965 B. s. FORMAN CARBURETOR NEEDLE VALVES Filed Aug. 20, 1962 FQqr/ United States Patent C) 3,166,292 CARBURETOR NEEDLE VALVES Benjamin G. Forman, Massapequa, N.Y., assignor to Formar Industries, Inc., New York, N.Y., a corporation of Illinois Filed Aug. 20, 1962, Ser. No. 218,059 1 Claim. (Cl. 251-215) This invention relates generally to the field of needle valves, and more particularly to an improved carburetor needle valve having self-contained means for frictionally retaining a given adjustment.

In the prior art construction, valves of this type are normally threadedly engaged within a carburetor body in such manner that the pointed end thereof is disposed adjustably within a comically-shaped needle valve seat, so that rotation of the valve within the body results in movement of the pointed end to one of a plurality of positions with respect to the needle valve seat. To maintain a given adjustment, coil spring means is interposed between the head portion of the valve and the body of the carburetor whereby the friction existing between the threaded interconnection is increased. As the interconnecting threaded portions are both of relatively rigid nonresilient material, eg steel, undamped vibration existing in every internal combustion engine will, with passage of time, disturb the relation between the threaded parts, resulting in misadjustment and the necessity of manual readjustment.

It is among the principal objects of the present invention to provide an improved form of carburetor needle valve in which the outer surface thereof is formed of a distortable synthetic resinous material having misaligned threads thereon, the same being capable of engaging a normally machined threaded opening and with slight distortion thereof of maintaining the same in fixed adjusted position in such manner as to be insensitive to normal vibration.

Another object of the invention lies in the provision of an improved carburetor needle capable of frictionally maintaining itself in adjusted position without the use of springs or other resilient auxiliary elements.

Still another object of the invention lies in the provision of an improved carburetor needle of the class described which may be conveniently manufactured using injection molding techniques, and with a minimum of expensive machining operations.

Yet another object of the invention lies in the provision of an improved carburetor needle possessed of the above advantages, in which the total cost of production may be of a reasonably low order, directly comparable with that of existing prior art devices, thereby permitting consequent wide distribution and use.

A feature of the invention lies in the fact that the device may be incorporated into existing carburetor structures, without the necessity of modifying the same.

These objects and features, as well as other incidental ends and advantages, will more fully appear in the progress of the following disclosure, and be pointed out in the appended claims.

In the drawing, to which reference will be made in the specification, similar reference characters have been employed to designate corresponding parts throughout the several views.

FIGURE 1 is a view in elevation showing a first embodiment of the invention.

FIGURE 2 is an end elevational view thereof, as seen from the right-hand portion of FIGURE 1.

FIGURE 3 is a centnal longitudinal sectional view thereof, partly in elevation.

FIGURE 4 is a view in elevation corresponding to ice that seen in FIGURE 1, but showing a second embodiment of the invention.

FIGURE 5 is an end elevational view of the second embodiment as seen from the right-hand portion of FIG- URE 4.

FIGURE 6 is a central longitudinal sectional view of the second embodiment, partly in elevation.

FIGURE 7 is a central longitudinal sectional view of the first embodiment, partly in elevation, showing the device in installed condition upon a conventional carburetor.

- In accordance with the first embodiment of the invention, the device, generally indicated by reference character 10, is illustrated in FIGURE 7 in installed condition within a conventional carburetor 11, the body of the carburetor having a. threaded opening 12, and a needle valve seat 13, as is well-known in the art. The device 10 comprises broadly: a centrally disposed core element 15 and an outer threaded sleeve element 16.

The core element 15 is preferably formed of cold rolled steel, as a screw machine product, and includes an elongated shaft 18 having a pointed end 19 thereon. Adjacent the pointed end is a conical surface 20 corresponding to the conical surface 21 forming the valve seat 13. The outer surface 22 of the shaft 18 is generally cylindrical, and includes a knurled portion 23 normally disposed within the outer sleeve element 16. The outer end 24 is preferably flush with the sleeve element 16, and includes a tool-engaging recess 25.

The outer sleeve element 16 is formed of molded synthetic resinous material, preferably as a result of insert molding techniques which permit the positioning of a finished core element 15 to be inserted within the mold (not shown) and the injection of the synthetic resinous material thereabout to form the sleeve element 16 upon the core element 15. I have found nylon to be a suitable material, but other similar synthetic resinous materials may be employed. The sleeve element 16 includes a head member 29 having an end surface 30 and polygonal surfaces 31 permitting the engagement of a tool (not shown) to efifect adjustment. For manual adjustment, there is also provided a radially-extending finger-engaging tab 32.

Surrounding the knurled portion 23 of the shaft 18 is a cylindrical portion 33 having a threaded outer surface 34 thereon, the threads being distorted either in cross sectional shape or pitch with respect to the threads of the opening 12 to a small degree, as best seen in FIGURE 7, so that upon threaded engagement therebetween, the threaded portion 34 is slightly distorted to provide a tight fit between the threads which is not sensitive to vibration. Where a synthetic resinous material such as nylon is used, the toughness of the material and its limited flexibility under heavy stress creates more than adequate friction to retain an adjustment. The friction created is sufiicient to permit the elimination of the conventional coil spring beneath the head of the valve as employed in conventional constructions.

Turning now to the second embodiment of the invention, as illustrated in FIGURES 4, 5 and 6, parts corresponding to those of the first embodiment have been designated by similar reference characters with the additional prefix 1.

The second embodiment differs from the first embodiment principally in the provision of an enlarged head 40 having a cylindrical surface 41 of diameter greater than that of the surface 122, and which extends partially outwardly of the outer sleeve element 116. To transmit a superior transmission of torque from the sleeve 116 to the core element 118, the core element is provided with one or more transverse bores 150, through which the material comprising the sleeve element 116 may fiow dur- 1) ing injection-molding, so that upon the curing of the material, a positive interconnection is formed, Where it is not necessary to rely upon the knurling at 123.

I wish it to be understood that I do not consider the invention limited to the precise details of structure shown and set forth in this specification, for obvious modifications will occur to those skilled in the art to which the invention pertains.

I claim:

In an improved carburetor needle valve, a body member having a threaded opening, a metallic centrally disposed core element, and a synthetic resinous outer sleeve element, said core element including an elongated shaft having a conically-shaped inner end thereon, and a cylindrical surface; said outer sleeve element having a toolengaging means on an outer end thereof, and having a cylindrical core corresponding in diameter to that of the cylindrical surface of said core element, and having a threaded outer cylindrical surface; the threads on said threaded outer cylindrical surface being misaligned with respect to said body opening threads and mechanically distortable upon the engagement of the same within said threaded opening.

References Cited in the file of this patent UNITED STATES PATENTS 1,392,547 Willis Oct. 4, 1921 1,674,029 Welch June 19, 1928 1,912,994 Oishei et a1 June 6, 1933 2,701,119 Smith Feb. -1, 1955 2,926,885 Szulcet al Mar. 1, 1960 2,942,407 Morin June 28, 1960 

